Are Power Inverters Safe?

Power inverters are a great tool to have with you no matter the situation. It could be that you are going for a long road trip with the family and you want to power a television to keep the kids entertained or perhaps you are camping off grid and want to a warm cup of coffee in the morning. Whatever the reason you need it for a power inverter will give you a supply of alternating current (AC) power so that you can run your standard electronics or appliances that you normally find in your home. This is done by hooking the power inverter directly up to your vehicle’s battery. The inverter then draws the stored direct current (DC) energy in your battery over to the AC energy that your appliances need.

While the overall concept of power inverters is widely understood there are still a lot of questions on the topic. What size do I need? How to install them? Over the past few weeks here at we have been doing our best to answer all of these questions in various articles. The goal being to provide our readers with a one stop source for all things power inverters. Today’s topic is exactly how safe are these inverters? What should you be concerned with when running them?

Are Power Inverters Safe?

Let me first say that power inverters are very safe. There is a very low risk of fire or other calamity when running one of these tools in your vehicle. That being said, there are a few things that can happen when running a power inverter that can have lasting consequences. Let’s take a look:


Installing your inverter correctly is key to getting optimal performance as well as being safe. The power inverter you purchased should come with an installation guide that will take you step through step on how to hook up the inverter. The good news is that the installation of these tools is actually quite basic and does not take much time. Before install ensure that the cables look to be in good quality and that there is no fraying or damage to them.

Exceeding Rated Wattage

A big gotcha when it comes to power inverters is purchasing the wrong sized power inverter for your needs. Inverters come in all different sizes ranging from a few hundred watts all the way up to four or five-thousand watts. The size that you need is determined by the total wattage of the appliances or electronics that you wish to plug-in into the inverter.

In some cases the total wattage on an appliance will be shown on the product label. In other cases though the wattage is not shown. No need to worry though as you should be able to find the total amperage or amps on the label. If you have the amperage number then all you have to do is take the amp number and multiply by the volts. Volts are just a measurement of what type of plug-in the appliance uses. When it comes to power inverters you will be using a one-hundred and twenty volt plug-in.

So, the math becomes  amps times volts equals watts. As an example, lets say you want a warm cup of coffee in the morning. The coffee machine is six amps. The math is now six amps times one-hundred and twenty volts equals seven-hundred and twenty watts. Once you have the total wattage of the appliances you wish to plug-in into the inverter it is also best to add an additional twenty or thirty percent. This gives you a buffer zone so if you miscalculated the total wattage or if you want to plug-in an additional appliance you have the extra wattage.

If the wattage of the appliance exceeds that of the power inverter rated wattage then you can overload your power inverter. The power inverter you are dealing with should have a built-in surge protector. If you overload the inverter the surge protector will shut the inverter off automatically. A few seconds later the inverter will turn on again to check to see if the wattage level has changed. If it has not then it will shut down again. This process repeats numerous times until at last the inverter shuts off entirely. It is vital that you purchase the correctly sized power inverter for your application.

Length of Time

The other thing to look at when it comes to power inverters is the length of time that you can use them. This depends on how you wish to run your power inverter. If you will have the inverter plugged in and running while your vehicle’s engine off then the power it needs is going to be pulled directly from your vehicle’s battery. The standard battery in your vehicle is a twelve volt cranking battery. It is meant for short bursts of power to start your engine. It is NOT meant for long term extended use such as with a power inverter.

If you use an inverter with the engine off then you can only really expect your battery to last between thirty to sixty minutes before the battery has been drained entirely. You are then left with a dead battery with no way to start your vehicle without a jump. Even if you do get a jump start and get your vehicle running again you have permanently damaged your starting battery. These cranking batteries are not meant to fall below ninety percent capacity. Letting the battery drain below that will cause damage and shorten the battery’s lifespan.

Now if you wish to use your inverter with your vehicle’s engine on then it is a whole different story. When the engine is on the alternator is running. The alternator provides continuous power to your battery. As the inverter draws power from the battery the alternator works to recharge the battery at the same time. In essence your inverter will run indefinitely until you turn the vehicle off or your engine runs out of gasoline. In my opinion this is the best and safest way to run a power inverter.

Earlier I stated that the standard battery is only good at ninety percent capacity or higher and that they do not last long under a power inverter load. What you can do though is look at installing a secondary battery for your vehicle. This secondary battery will be charged by your alternator just like the other but it will give you an alternative source of power for your power inverter. When going this route it is key that you purchase deep cycle battery as your secondary battery.

Deep cycle batteries are intended for long term usage. They can be used for hours, sometimes even days, at a time. They can fall as low as fifty percent capacity as well. One key thing to mention here is that you will need BOTH a standard cranking battery AND a deep cycle battery. The cranking battery is necessary to start your car and the deep cycle is used to power your power inverter. Another point to mention here is that deep cycles can take a significant amount of time to charge. Because of this some folks will opt for a higher output alternator as well. Remember that both batteries have to be charged by your alternator and if you have a higher output alternator then you will be able to charge both batteries faster.

Installing a secondary battery can be a bit tricky. If you are an experienced tinkerer with vehicles the you should be able to handle it by following this guide that I found. However, if you are no as comfortable working on vehicles then I recommend taking your vehicle into the dealership or a local mechanic and tell them that you want a secondary deep cycle battery installed. If you also already have the power inverter purchased you can ask them to install it as well. Otherwise, you can install it after the fact.


In conclusion folks power inverters are very safe. The only things you have to look out for when running them is that you installed them correctly, you have adequate wattage to handle your needs, that you run the inverter while your engine is running, or if you run the inverter with the engine off ensure that you have a secondary deep cycle battery installed to ensure that your inverter can run for hours at a time.

I hope this article was helpful,

Alec Johnson

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